Trimethylsilyldiazomethane in the preparation of diazoketones via mixed anhydride and coupling reagent methods: a new approach to the Arndt-Eistert synthesis

Reaction or trimethylsilyldiazomethane with a mixed anhydride derived from a carboxylic acid by the action of ethyl chloroformate, yields the correspo nding diazoketone in high yield, Subsequent Wolff rearrangement of the diaz oketone leads to the homologated ester. Reaction of trimethylsilyldiazometh ane with carboxylic acid-dicyclohexylcarbodiimide mixtures leads to the for mation of diazoketone and trimethylsilylmethyl ester in equimolar ratio via an acid anhydride intermediate. The N-hydroxysuccinimide ester of the acid does not react with trimethylsilyldiazomethane or with its more reactive l ithiated derivative. (C) 2001 Elsevier Science Ltd. All rights reserved.